Under Get Information – Create/Modify User Commands, add a line that runs the command below. Works nicely on HP workstations, it does pad the value with “SerialNumber ” but that’s workable.
If you have changed a board, and also not all BIOS codes are actually pre-entered. In that case it is necessary to boot into the BIOS of a machine with that issue, and enter it manually (from reading it off of the hardware itself.) In other words, if the machine is not very old, the response you are getting is the default response when no value is set (null).